The present invention relates to an ultrasonic medical device, and more particularly to an apparatus and method of using an ultrasonic probe with a pharmacological agent to treat an occlusion and effectively remove the occlusion and prevent subsequent occlusion formation and other health risks.
Vascular occlusive disease affects millions of individuals worldwide and is characterized by a dangerous blockage of vasculatures. Vascular occlusive disease includes thrombosed hemodialysis grafts, peripheral artery disease, deep vein thrombosis, coronary artery disease, heart attack and stroke. Vasculatures include veins, arteries, blood vessels, intestines, ducts and other body lumens that materials may flow through. Heart attacks are an especially common vascular occlusive disease, with an approximate annual rate of 800,000 people in the United States having acute heart attacks with approximately 213,000 of those people dying. Strokes are also common, with approximately 80% of all strokes being ischemic strokes caused when a vascular occlusion formed in one part of the body travels to a smaller blood vessel in the brain and inhibits blood flow to the brain. Vascular occlusions (clots, intravascular blood clots or thrombus, occlusional deposits, such as calcium deposits, fatty deposits, atherosclerotic plaque, cholesterol buildup, fibrous material buildup, arterial stenoses) result in the restriction or blockage of blood flow in the vasculatures in which they occur. Occlusions result in oxygen deprivation (xe2x80x9cischemiaxe2x80x9d) of tissues supplied by these blood vessels. Prolonged ischemia results in permanent damage of tissues which can lead to myocardial infarction, stroke or death. Occlusions frequently occur in coronary arteries, peripheral arteries and other blood vessels.
The disruption of an occlusion can be affected by mechanical methods, ultrasonic methods, pharmacological agents or combinations of all three. Many procedures involve inserting an insertion lumen into a vasculature of a body. Insertion lumens include, but are not limited to, probes, catheters, wires, tubes and similar devices.
Mechanical methods of treating thrombolysis include balloon angioplasty, which can result in ruptures in a blood vessel, and is generally limited to larger blood vessels. In addition, scarring of vessels is common, which may lead to the formation of a secondary occlusion (a process known as restenosis). Another common problem is secondary vasoconstriction (classic recoil), a process by which spasms or an abrupt closure of the blood vessel occurs. These problems are common in treatments employing interventional devices. In traditional angioplasty, for instance, a balloon catheter is inserted into the occlusion, and through the application of hydraulic forces in the range of about ten to about fourteen atmospheres of pressure, the balloon is inflated. The non-compressible balloon applies this significant force to compress and flatten the occlusion, thereby opening the vessel for blood flow. However, these extreme forces result in the application of extreme stresses to the vessel, potentially rupturing the vessel, or weakening it and thereby increasing the chance of post-operative aneurysm, or creating vasoconstrictive or restenotic conditions. In addition, the particulate matter forming the occlusion is not removed, rather it is just compressed. Other mechanical devices that drill through and attempt to remove an occlusion have also been used, and create the same danger of physical damage to blood vessels.
Ultrasonic probes using ultrasonic energy to fragment body tissue have been used in many surgical procedures (see, e.g., U.S. Pat. No. 5,112,300; U.S. Pat. No. 5,180,363; U.S. Pat. No. 4,989,583; U.S. Pat. No. 4,931,047; U.S. Pat. No. 4,922,902; and U.S. Pat. No. 3,805,787). Ultrasonic devices used for vascular treatments typically comprise an extracorporeal transducer coupled to a solid metal wire which is then threaded through the blood vessel and placed in contact with an occlusion (see, e.g., U.S. Pat. No. 5,269,297). In some cases, the transducer, comprising a bendable plate, is delivered to the site of the clot (see, e.g., U.S. Pat. No. 5,931,805).
Some ultrasonic devices include a mechanism for irrigating an area where the ultrasonic treatment is being performed (e.g., a body cavity or lumen) in order to wash biological material from the area of treatment. Mechanisms used for irrigation or aspiration known in the art are generally structured such that they increase the overall cross-sectional profile of the elongated probe, by including inner and outer concentric lumens within an ultrasonic probe to provide irrigation and aspiration channels. In addition to making the probe more invasive, prior art probes also maintain a strict orientation of the aspiration and the irrigation mechanism, such that the inner and outer lumens for irrigation and aspiration remain in a fixed position relative to one another, which is generally closely adjacent to the area of treatment. Thus, the irrigation lumen does not extend beyond the suction lumen (i.e., there is no movement of the lumens relative to one another) and any aspiration is limited to picking up fluid and/or tissue remnants within the defined area between the two lumens.
As discussed above, medical devices utilizing ultrasonic energy to destroy material comprising an occlusion in the human body are known in the art. A major drawback of prior art ultrasonic devices comprising a probe for occlusion removal is that the devices are relatively slow in comparison to procedures that involve surgical excision. This is mainly attributed to the fact that such ultrasonic devices rely on imparting ultrasonic energy to contacting occlusions by undergoing a longitudinal vibration of the probe tip, wherein the probe tip is mechanically vibrated at an ultrasonic frequency in a direction parallel to the probe longitudinal axis. Thus, the treatment area is localized at the probe tip, which substantially limits its ability to ablate large occlusion areas in a short time. An ultrasonic medical device with a multiple material coaxial construction for conducting axial vibrations is known in the art (see, e.g., U.S. Pat. No. 6,277,084). In addition to prior art ultrasonic devices being slow, previous ultrasonic methods of treating plaque still include many undesirable complications and dangers to the patient.
The use of a pharmacological agent alone to treat a vascular occlusion is common, but suffers from a variety of limitations that compromise the effectiveness of the removal of the vascular occlusion. It is difficult to disperse the pharmacological agent symmetrically to the vascular occlusion, thereby leaving portions of the vascular occlusion untreated. Often, portions of the vascular occlusion are carried downstream of the site of the vascular occlusion and lead to further problems including embolism. In addition, delivery of the pharmacological agent is inefficient and infusion times are long as the agent naturally dissolves into areas of the vascular occlusion. Adverse complications such as hemorrhages and bleeding are also common, thereby creating additional health risks beyond those presented by the vascular occlusion. Finally, large quantities of the pharmacological agent are needed to treat the thrombus, thereby driving up the cost of the treatment.
Prior art attempts to safely and effectively ablate an occlusion in a vasculature of a body have been less than successful. U.S. Pat. No. 6,508,782 to Evans et al. discloses a catheter for dissolving blockages in tissues. The Evans et al. device uses a catheter with an inflatable member either alone or in conjunction with a medicament for dissolving the blockages. The Evans et al. device discloses a catheter with an inflatable member near the distal tip of the catheter to prevent the blockage from passing downstream of the blockage and a perfusion channel for removal of the broken up blockage. The Evans et al. device is complicated, unreliable and necessitates a time consuming procedure that requires the exchange of various lumens to deliver the medicament and to vibrate the Evans et al. device. Since vibratory motion for the Evans et al. device is longitudinal and at a distal tip, the Evans et al. device does not focus on all parts of the blockage and does not effectively and efficiently remove the blockage. Therefore, there remains a need in the art for effectively ablating an occlusion that combines the ultrasonic energy of an ultrasonic probe with the dissolving effects of a pharmacological agent that is simple, quick, reliable, efficient, effective, does not harm healthy tissue and continues to break up particulate of the occlusion downstream to prevent occlusion formation downstream.
U.S. Pat. No. 5,925,016 to Chomenky et al. discloses a system and a method for treating thrombosis by moving drugs through the thrombus by pressure. The Chornenky et al. device isolates the thrombus by using a catheter with an occlusion balloon proximal to the thrombus, a guide wire with an occlusion placed distal to the thrombus, and an infusion catheter that delivers drugs distal to the thrombus through pressure. Since the Chomenky et al. device relies on the drug and the non-symmetric pressurized delivery of the drug to remove the thrombus, the thrombus is not effectively removed and may result in complications downstream of the thrombus. The Chornenky et al. device uses a time consuming procedure that imparts high stresses to the vessel walls that can damage the vessel. Therefore, there remains a need in the art for effectively ablating an occlusion that combines the ultrasonic energy of an ultrasonic probe with the dissolving effects of a pharmacological agent that is simple, quick, reliable, efficient, effective, does not harm healthy tissue and continues to break up particulate of the occlusion downstream to prevent occlusion formation downstream.
U.S. Pat. No. 6,280,413 to Clark et al. discloses a thrombolytic filtration and drug delivery catheter comprising a shaft and longitudinal ribs that are compressed when moved to the treatment site and expand to a diameter greater than the shaft of the catheter. In the Clark et al. device, drugs are delivered through a lumen in the catheter and are delivered through ports in the ribs. Since the Clark et al. device relies on the non-symmetric dispersion of the drug, the Clark et al. device does not effectively remove an occlusion and the occlusion can reform downstream. The Clark et al. device is complicated and relies on a separate lumen to remove the particles of the thrombus. In addition, the longitudinal ribs of the Clark et. al. device can impart high stresses to the vasculature and harm healthy tissue. Therefore, there remains a need in the art for effectively ablating an occlusion that combines the ultrasonic energy of an ultrasonic probe with the dissolving effects of a pharmacological agent that is simple, quick, reliable, efficient, effective, does not harm healthy tissue and continues to break up particulate of the occlusion downstream to prevent occlusion formation downstream.
The prior art attempts of removing an occlusion from a vasculature in a body are complicated, expensive, unsafe, ineffective, time consuming, inefficient and compromise the health of a patient by potentially allowing the occlusion to reform downstream. Therefore, there remains a need in the art for effectively ablating an occlusion that combines the ultrasonic energy of an ultrasonic probe with the dissolving effects of a pharmacological agent that is simple, quick, reliable, efficient, effective, does not harm healthy tissue and continues to break up particulate of the occlusion downstream to prevent occlusion formation downstream.
The present invention relates to an ultrasonic medical device, and more particularly to an apparatus and method of using an ultrasonic probe with a pharmacological agent to treat an occlusion and effectively remove the occlusion and prevent subsequent occlusion formation and other health risks.
The present invention is an ultrasonic medical device comprising an ultrasonic probe and a catheter surrounding a length of a longitudinal axis of the ultrasonic probe used with a pharmacological agent. In a preferred embodiment of the present invention, the catheter delivers the pharmacological agent to treat the occlusion. In a preferred embodiment of the present invention, the pharmacological agent is tissue plasminogen activator (tPA). The pharmacological agent enhances an occlusion treatment effect of the ultrasonic probe.
The present invention is an ultrasonic medical device comprising an elongated, flexible probe and a catheter surrounding a length of a longitudinal axis of the elongated, flexible probe. A pharmacological agent moves through the catheter and enhances an effect of a transverse ultrasonic vibration of the elongated, flexible probe to treat the occlusion. The transverse ultrasonic vibration of the elongated, flexible probe produces a plurality of transverse nodes and transverse anti-nodes along a portion of the longitudinal axis of the elongated, flexible probe.
The present invention provides a method of treating an occlusion through the combined effects of an ultrasonic probe and a pharmacological agent. The ultrasonic probe is inserted into a vasculature, a catheter is delivered over a length of a longitudinal axis of the ultrasonic probe and a pharmacological agent is released through the catheter. A section of the longitudinal axis of the ultrasonic probe is exposed to the occlusion and an ultrasonic energy source is activated. The pharmacological agent continues to move downstream of a site of the occlusion to work in conjunction with the ultrasonic probe to reduce the occlusion to a size that can easily be removed from the body in conventional ways or simply dissolve into the blood stream.
The present invention provides a method of removing an occlusion by moving an elongated, flexible probe through a vasculature to a site of an occlusion, releasing a pharmacological agent in the vasculature and activating an ultrasonic energy source to vibrate a longitudinal axis of the ultrasonic probe. The pharmacological agent enhances an occlusion destroying effect of the elongated, flexible probe.
The present invention is an ultrasonic medical device and a pharmacological agent used together to treat an occlusion and efficiently remove the occlusion to prevent subsequent reformation of the occlusion and other health risks. The present invention provides an apparatus and a method for more completely removing an occlusion that is safe, simple, efficient, effective, user-friendly, reliable and cost effective.